Delay arming apparatus



Feb.13,1968 T. J. O'CONNOR ETAL 3,368,487

DELAY ARMING APPARATUS Filed Feb. 27, 1967 2 Sheets-Sheet 1 43 g Louis J. deSabla 45 39 7 BY 0. (W Fig. 4a Fig. 4b

ATTORNEY v INVENTOR Timothy J. O'Connor Feb. 13, 1968 T. J. O'CONNOR ET AL DELAY ARMING APPARATUS Filed Feb. 27, 1967 2 Sheets-Sheet 2 I JIMI Hg 5 4, INVENTOR ARM'NG Timothy J. O'Connor ClRCUiT U S J. deSablO United States Patent 3,368,487 DELAY ARMING APPARATUS Timothy J. OConnor, Rockville, and Louis J. De Sabla, Silver Spring, Md., assignors to the United States of America as represented by the Secretary of the Navy Filed Feb. 27, 1967, Ser. No. 619,538 6 Claims. (Cl. 102-70.2)

ABSTRACT 0F THE DISCLOSURE A delay earming device utilizing an iac'cleratio-n force responsive mass lafiixed to a rack gear. A pair of switch contacts is closed by the travel of the track gear. The rack gear engages a flywheel through a gear train. The flywheel ia'ctu ates a pair of rotating discs having 'arcuate outout portions which come into alignment with each other only when the flywheel has rotated a prescribed number of revolutions. When alignment of the discs occurs, \a stepping relay operated by the closing of the rack gear switch contacts rotates a switch into a closed position, thereby energizing an arming circuit.

Background 0 the invention This invention relates generally to timing devices and more particularly to an acceleration responsive delay arming mechanism for an aerial or'dnan'ce vehicle such as a missile.

Aerial weapons systems must have the capability of deliver-ing a payload to a target area with assurance of safety to friendly personnel and territory. To [provide such a safety feature in missiles, delay arming devices :are inco-rporated into the missile such that the missile remains in an unarmed condition until it is at a point in the trajectory known as a safe separation distance at which point the missile is armed by the device. In earlier types of missiles, the safe separation distance was usually considered to Ibe at motor burn-out at which point the missile ceases to accelerate :and begins Ito coast. In such missiles, accelerometer ty pe delay devices which operated environment-ally during the acceleration or boost phase of the missile flight served satisfactorily to arm the missile at the point of motor lb'urn out. In newer type missiles, however, with more powerful warheads it is necessary that the safe separation distance he extended into the coast phase of the missile trajectory to provide the adequate degree of safety.

The increase in safe separation distance has been provided in present day delay arming devices 'by a combination of an accelerometer and la timer which is triggered by the accelerometer iat the end of the motor 'blJlIl-O-Il t and extends the delay into the coast phase. Such combined delay devices, however, suffer from two distinct disadvantages. One dis-advantage is that the timer depends ulpon the operability of the accelerometer for the initiation of the timer. In other words, the delay arming system depends upon the proper operation of two separate devices, the second device of which depends upon the first for its operation. The other disadvantage is that the timer is non-environmental. That is, the timer :aots after a given time period, independently ot the acceleration, velocity and hence the distance travelled by the associated missile during this portion of the delay time.

Summary of the invention It is an object of this invention to provide an accelerometer type delay arming device 'for a missile which is environmentally operative into the coast phase of the missile travel.

It is another object of this invention to provide an inertially operated type delay armin-g device for Ian aerial vehicle which operates as a function of the distance the vehicle has traveled.

in accordance with the preferred embodiment of this invention, these and other objects are attained by an inertial mass which is connected through ia gear train to a flywheel. During the acceleration phase, the acceleration forces on the inertial mass cause it to move and to drive the flywheel. During the coast rphase both the mass and the flywheel are in motion. However, the device is operating environmentally in the coast phase inasmuch as any deceleration forces acting on the inertial mass will cause it to slow down and prolong the time delay in accordance with the actual distance the missile has traveled. A switch on the inertial mass and a switch associated with the gear train must both close before the missile is armed.

Brief description of the drawings A more complete appreciation of the invention and many of the attendant advantages thereof will readily be appreciated 'as the same 'becomes better understood Iby reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. '1 is a perspective view illustrating the arming mechanism of the instant invention;

FIG. 2 is a top view of the locking arrangement for the inertial mass prior to launching;

FIG. 3 is a side view of the locking arrangement for the inertial mass;

FIGS. 4A and 4B illustrate the relative positions of the discs of the gating apparatus in their closed and open positions; and

FIG. 5 is a schematic view of the electrical circuitry used with this invention.

Description of the preferred embodiment Referring to FIG. 1 of the drawings, a delay arming device is shown in which an inertial mass 11 is fixedly attached to a rack gear 12 for movement therewith. Rack gear 12 is connected to a flywheel -13 through a gear train which includes a pinion 15 meshing with rack gear 12 and a gear 17 which is connected to pinion 15 through a shaft 19, gear 17 engaging a pinion 21 for rotational movement therewith. A shaft 23 connects pinion 21 to a gear 25 which engages a pinion gear 27 mounted on a shaft 29. Shaft 29 extends through a flywheel 13 and is fixedly attached thereto for rotation therewith. Shaft 29 provides a'take-oif for a revolution indicator and gating apparatus.

The revolution indicator and gating apparatus includes gears 31 and 33 which engage a pinion gear 35 affixed to the shaft 29. Gears 31 and 33 may have discs 37 and 39 respectively afiixed thereto with arcuate cutout portions or sectors 41 and 43 formed in the circumferential surfaces thereof.

A rotary electrical switch 45 is mounted on a shaft 47 which is disposed in parallel relationship to shaft 29, switch 45 having an arcuate shaped lug 49 affixed to the circumference thereof for operational engagement with discs 37 and 39. The relative angular positions of discs 37 and 39 determine whether or not switch 45 may be activated as will be described more fully hereinafter.

Shaft 47 also carries gears 51 and 53. Gear 51 engages a gear 55 which is mounted on a shaft 57. An actuating solenoid 59 is also mounted on shaft 57. Gear 53 engages a gear 61 which is connected through a shaft 62 to a releasable mechanical locking member 63 having a slot 64 formed therein.

Inertial mass 11 is slideably mounted on a shaft or rod 65 and carries, at the top extremity thereof, two

electrical switch contact bars 67 and 69 which at the upper limit of travel of inertial mass 11 will simultaneously contact switch terminals 71 and 73 respectively. The inertial mass is composed of electrically conductive material such as steel to form a short circuit between switch contact bars 67 and 69.

In FIGS. 2 and 3, the relationship between the locking device 63 and the inertial mass 11 is illustrated as being effected by a spring loaded weight 75 which is slideable on a pair of parallel spaced rods 77 and 79. Rods 77 and 79 are mounted at their extremities to a missile housing 80. Weight '75 is biased by springs 81 and 82 which normally urge the Weight against inertial mass -11, holding the mass in an initial position prior to launching. The weight 75 is also held from moving by the slot 64 of locking member 63 which initially is perpendicular to a ridge 83 formed on weight 75. When slot 64 is aligned with ridge 83, as shown, the weight 75 is free to move along rods 77 and 79 under the influence of accelerating forces acting on the missile housing 80. Locking means for locking the weight 75 may be provided by a latch 84 on a latch body 85 which is mounted on hOusing 80. Latch 84 resiliently projects from latch body 85 and will engage a notch 86 formed in weight 75 to lock Weight 75 at the extreme of its moved position.

Referring to FIGS. 2, 4A and 4B, the discs 37 and 39 and lug 49 will assume varying angular relationships with respect to each other as the inertial mass 11 moves. In the initial position of the inertial mass, the angular relationship of discs 37 and 39 and lug 49 of switch 45 will be that as shown in FIG. 4A. In this position, the arcuate cutout portions 41 and 43 are separated and switch 45 is restrained from rotation by the interference of lug 49 with discs 37 and 39.

It is to be noted that gear 31 may have a slightly different number of teeth than gear 33. For example, gear 31 may have 60 teeth and gear 33 may have 65 teeth. This difference in the number of teeth provides for a continuously varying angular relationshi between the discs 37 and 39 as the inertial mass 11 moves and flywheel 13 rotates. When the inertial mass 11 has reached the end of its travel, the discs 37 and 39 will have moved to the angular relationship shown in FIG. 4B, with arcuate cutout portions 41 and 43 being in respective angular positions to form effectively a larger arcuate cutout portion which provides clearance for lug 49 to pass through such that switch 45 may be rotated to close the electrical contacts therein. The discs, gear train and flywheel thus provide apparatus for indicating the travel of the inertial mass and provide a fail-safe device for arming. The fail-safe feature is provided by the need for both contact bars 67 and 69 to be in contact with terminals 7 1 and 73 and for the flywheel to have rotated sufliciently for the discs 37 and 39 to be positioned as shown in FIG. 4B. If any of the gears should become stripped and the inertial mass should travel to the end of its path earlier than the normal delay time, the flywheel will not have rotated suificiently to align sectors 41 and 43 and switch 45 cannot be closed, thus a safety hazard occasioned by a premature arming of the missile is prevented.

The inertial mass 11 together with the gear train and flywheel 13 define a double integrating accelerometer inasmuch as the acceleration forces acting on the mass will be translated into a distance travelled by the inertial mass, which distance is proportional to the distance travelled by the missile.

As may be seen by reference to the electrical circuit of FIG. 5, upon contact of bars 67 and 69 with terminals 71 and 73, the rotary solenoid 59 is energized through an energy source 87. The solenoid 59 which is mechanically connected to the rotor of switch 45 will cause the contacts of switch 45 to close and energize a conventional arming circuit 89 through an energy source 91. Solenoid 59 is also mechanically connected through gears 55, 51,

53 and 61 to locking member 63 which will rotate with the rotation of the solenoid shaft. A switch 93 may be provided for adjusting the position of slot 64 prior to launching. A resetting switch 95 may be connected to a circuit including an energizing source 97 for rotating the locking device 63 during prelaunch testing. Both switch 93 and 95 may be of the push-button type which will normally be open unless pressure is applied.

In operation, inertial mass 11 is initially held in the starting position by weight 7 5. Prior to missile launching, the slot 64 of locking rotor 63 will be perpendicular to ridge 83 thereby locking weight 75 in place. When the missile is to be launched, switch 93 is closed and solenoid 59 will rotate, causing a rotation of locking rotor 63 with slot 64 thereof coming into alignment with ridge 83 to free weight 75 for movement along rods 77 and 79. When the missile is launched, the acceleration forces will cause weight 75 to move to the end of its path of travel, at which point it is locked in this position by the operation of latch 84. At the same time, the accelerating forces acting on inertial mass 11 will cause it to move and flywheel 13 to rotate by the operation of the gear train which includes gears 15, 17, 21, 25 and 27. This gear train provides a step up gear ratio to provide the necessary torque absorption by the flywheel to attain the desired travel rate of the inertial mass 11. With flywheel 13 rotating, the delay timing has begun, the movement of inertial mass 11 being proportional to the number of revolutions of flywheel 25. As the flywheel rotates, cutout portions 41 and 43 will gradually come into position for arming, as shown in FIG. 4B, the time for such positioning being equal to the time for the inertial mass 11 to travel the extent of its path and the flywheel to rotate a predetermined number of revolutions, for example, 50 revolutions. With cutout portions 41 and 43 in the aligned position as shown in FIG. 4B, clearance is provided for lug 49 and switch 45 to rotate. At the end of the path of travel of inertial mass 11, contact bars 67 and 69 will be in contact with terminals 71 and 73, causing solenoid 59 to be actuated which causes switch 45 to be rotated, closing the contacts therein. The arming circuit 89 is activated and the missile is now in an armed condition.

The delay arming operation described above takes place over the acceleration phase and into a portion of the coast phase of the missile to provide the desired safe separation distance of the missile from its launching point. After the boost phase is completed that is, at motor burn-out, the flywheel and inertial mass are in equilibrium conditions of motion with neither applying a force to the other. Should deceleration forces be applied to the missile during the coast phase, the inertial mass will be acted upon by such deceleration forces which will tend to slow down the motion thereof. The deceleration forces acting on the inertial mass will also cause a torque to be applied to the flywheel to cause it to slow down. The delay arming device is thus environmental over the entire arming period'as the travel time for the inertial mass over its path of travel is dependent entirely on the acceleration and deceleration forces acting on the missile and the arming time will be directly proportional to the actual distance that the missile has travelled.

Obviously many modifications and variations of the present invention are made possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. An inertially operated delay arming device for a missile comprising,

a missile housing,

an inertial mass slideably mounted within said housing and being slideable from a first position to a second position,

first switch means on said mass, said first switch means being open when said mass is in said first position and closed when said mass is in said second position, mechanical gating means,

integrating means connecting said inertial mass to said gating means whereby said gating means will be opened by the movement of said inertial mass to said second position,

rotary second switch means,

rotary solenoid means, said solenoid means being electrically connected to said first switch means and mechanically connected to said second switch means whereby said solenoid will rotate said second switch to a closed position when said first switch means is closed, said missile being armed when said first and second switch means are closed, and

lug means on said rotary second switch means engaging said gating means and which permits said second switch means to move to a closed position only when said gating means is open.

2. An inertially operated delay arming device as in claim 1 in which said integrating means includes a first gear train connecting a flywheel to said inertial mass and a second gear train connecting said flywheel to said gating means.

3. An inertially operated delay arming device as in claim 2 in which said gating means comprise two disc portions on parallel shafts and connected to said second gear train, said disc portions being radially aligned and having cutout portions in the circumference thereof, said cutout portions being positioned to form a continuous arcuate path when said mass is in said second position.

4. Delay arming apparatus for a missile comprising,

a housing within said missile,

an inertial mass slideably mounted within said housing, said mass being slideable from an initial position to a final position,

releasable locking means for locking and releasing said inertial mass,

mechanical gating means, integrating means connecting said inertial mass to said gating means, said gating means being closed when said mass is in said initial position and open when said mass is in said final position,

first switch means on said inertial mass, said first switch means being open when said mass is in said initial position and closes as said mass reaches said final position,

rotatable second switch means engaging said gating means and being rotatable from an open position to a closed position when said gating means is open, said second switch means being connected to an arming circuit of said missile,

rotatable solenoid means connected to said second switch means for rotation thereof and to an energizing circuit including said first switch means whereby said second switch means may be rotated to a closed position when said first switch means is closed.

5. Delay arming apparatus as in claim 4 in which said integrating means includes a first gear train connecting said mass to a flywheel, and second gear train means connecting said flywheel to said gating means.

6. Delay arming apparatus as in claim 5 in which said second gear train comprises a shaft connected to said flywheel with a pinion thereon, a first gear engaging said pinion and having a disc aifixed thereto said disc having an arcuate cutout portion in the periphery thereof, a second gear engaging said pinion and having a second disc with an arcuate cutout portion in the periphery thereof, said first and second gears having a different number of teeth whereby the angular position of said first disc will continually vary with the angular position of said second disc as said pinion rotates.

UNITED STATES PATENTS No references cited.

BENJAMIN A. BORCHELT, Primary Examiner.

G. H. GLANZMAN, Assistant Examiner. 

